Fibre optic parametric amplifiers have been an important area of research during the last twenty years. However, several technological implications hinder their deployment in commercial communication systems. The work reported in this thesis has studied these implications both theoretically and experimentally with the aim of understanding the limitations of parametric processes and demonstrating practical subsystems for use in modern communication networks. The theoretical part of the project has analysed the various types of noise that are present in parametric amplifiers as well as their effects, both when an amplifier is considered on its own or as a part of a repeated transmission line. This task has been carried out on the basis of the statistical characterisation of the noise generated by parametric processes, providing an accurate description of the bit error rate induced by these nonlinear processes on modulated signals. The experimental part of this work presents the demonstration of two wavelength conversion schemes showing their feasibility for turn-key operation. The respective designs address wavelength division multiplexing (WDM) and spatial division multiplexing (SDM) settings. The performance of these devices is demonstrated through field trials in point-to point systems, optical switched networks and future SDM networks. The demonstration of wavelength conversion in SDM networks was based on the multi element fibre (MEF) technology. The features of this technology as an alternative implementation of SDM were experimentally demonstrated in transmission experiments. In addition, a critical comparison of the pros and cons of the actual implementations of SDM is provided.